The present invention relates to generator cooling and, more particularly, to a baffle plate for guiding cooling gas and improving end-core ventilation, to generators using such baffle plates, and to a method for generator cooling using such baffle plates.
During the process of producing electricity, power generators also create heat that must be dissipated away from the generator. Many known generators use fluid cooling to dissipate this heat. In many known generators, the fluid is a gas. Known gas-cooled generators are cooled by ventilated cooling systems that circulate the cooling gas through ducts in the rotor and stator.
In some known gas-cooled generators, a stator core is constructed by stacking many layers of magnetic laminations, also known as stator punchings. Ventilating ducts are defined between the stacked layers of magnetic laminations by providing spacers in the core stack, allowing for passage of cooling gas through the core during operation. The spacers are positioned in such a way to ensure tightness of the core during assembly and operation, and to avoid blocking or restricting the flow of gas through the stator. Outside space blocks are located at the ends of the generator stator core, between the stacked laminations and a stator flange 18. The cooling gas flow through the ventilation ducts between the stacked layers of laminations of the stator flows into a rotor-stator gap to define a rotor-stator gap flow.
As the ratings of conventional air-cooled generators increase, the challenge of cooling these generators also increases. Generator stator punchings are held together in the stator of a generator by stator flanges on either side. Heat is generated on these flanges as a result of electromagnetic fluxes from an end winding of the stator and axial fluxes from the core. Material considerations limit the maximum temperature of the flange. If proper cooling is not provided, insulation may fail, leading to malfunctioning of the generator. Thus, flange cooling may be required so that heat generated on the flange can be dissipated in a cooling medium. However, excessive flow through an outside space block (OSSB) may degrade overall performance of the generator and may cause reverse flow in outer stator ducts.